Biomedical subjects
Publications and source records attributed to W Herold.
Experiment 865 at the Brookhaven Alternating Gradient Synchrotron obtained 410 K+-->e(+)nue(+)e(-) and 2679 K+-->mu(+)nue(+)e(-) events including 10% and 19% background. The branching ratios were measured to be [2.48+/-0.14(stat)+/-0.14(syst)]x10(-8) (m(ee)>150 MeV) and (7.06+/-0.16+/-0.26)x10(-8) (m(ee)>145 MeV), respectively. Results for the decay form factors are presented.
A sample of 4 x 10(5) events from the decay K(+)-->pi(+)pi(-)e(+)nu(e) (K(e4)) has been collected in experiment E865 at the Brookhaven Alternating Gradient Synchrotron. The analysis of these data yields new measurements of the K(e4) branching ratio [(4.11+/-0.01+/-0.11) x 10(-5)], the s-wave pi pi scattering length [a(0)(0) = 0.216+/-0.013(stat)+/-0.004(syst)+/-0.005(theor)], and the form factors F, G, and H of the hadronic current and their dependence on the invariant pi pi mass.
A search for lepton flavor violating decays, K+ --> mu+ mu+ pi-, K+ --> e+ e+ pi-, K+ --> pi+ e+ mu-, K+ --> mu+ e+ pi-, and pi0 --> e+ mu-, was performed using the data collected in Experiment E865 at the Brookhaven Alternating Gradient Synchrotron. No signal was found in any of the decay modes. At the 90% confidence level, the branching ratios are less than 3.0x10(-9), 6.4x10(-10), 5. 2x10(-10), 5.0x10(-10), and 3.4x10(-9), respectively.
We report results of a search for the lepton-family number violating decay K+-->pi(+)&mgr;(+)e(-) from data collected by experiment E865 in 1996 at the Alternating Gradient Synchroton of Brookhaven National Laboratory. We place an upper limit on the branching ratio at 3.9x10(-11) ( 90% C.L.). Together with results based on data collected in 1995 and an earlier experiment, E777, this result establishes a combined 90% confidence level upper limit on the branching ratio at 2.8x10(-11). We also report a new upper limit on the branching ratio for pi(0)-->&mgr;(+)e(-) of 3.8x10(-10) ( 90% C. L.).
More than 400 K+-->pi(+)&mgr;(+)&mgr;(-) events were observed in a rare K+ decay experiment at the Brookhaven Alternating Gradient Synchrotron. Normalized to the K+-->pi(+)pi(+)pi(-) decay, the branching ratio is determined to be [9.22+/-0.60(stat)+/-0. 49(syst)]x10(-8). This branching ratio and the &mgr;&mgr; mass spectrum is in very good agreement with the measurement of the K+-->pi(+)e(+)e(-) decay, but deviates significantly from the previous measurement.
BACKGROUND: Intense activation of the sympathetic nervous system or administration of high concentrations of catecholamines diminishes myocardial contractility and produces infarct-like lesions throughout the heart. This study was conducted to determine whether norepinephrine-induced left ventricular (LV) dysfunction reverses with time and whether the histopathologic condition and the cardiac dysfunction produced by high doses of norepinephrine are causally related. METHODS: Norepinephrine, 10 microg bolus followed by 2.5 microg/kg/min for 90 minutes, was administered to conscious New Zealand white rabbits. Control rabbits (n=8) received saline solution. LV function was evaluated either immediately (n=7), on day 4 (n=8), or on day 10 (n=7) after norepinephrine treatment. Transverse sections from the left ventricle were then prepared for light microscopic study. RESULTS: Animals studied immediately after norepinephrine treatment demonstrated severe LV dysfunction and a decrease in global LV compliance. In contrast, LV function and compliance were normal in rabbits studied on day 4, but tissue sections from the left ventricle showed diffuse areas of inflammation. By day 10 the inflammatory process had progressed, and substantial collagen deposition had occurred. LV systolic function was normal, but a decrease in LV compliance was evident at this time. CONCLUSIONS: The normal LV systolic function on days 4 and 10 in spite of multiple foci of inflammation suggests (1) that norepinephrine-induced LV systolic dysfunction is reversible and (2) that the histologic derangements and the LV dysfunction are not causally related.
The electrophoretic mobility of vesicles is measured for concentrations of poly(ethylene glycol) from 0 wt.% to 10 wt.%. Mixtures of phosphatidylcholines and phosphatidic acid are used. The zeta potential calculated from the electrophoretic mobility and the viscosity of the suspension becomes more negative for all vesicles studied. Binding of poly(ethylene glycol) to the phospholipid surface by addition of the poly(oxyethylene)-containing surfactant C12E8 has the opposite effect and a decrease of the zeta potential is observed. Independent measurements of the surface potential of the vesicles in the presence of PEG by use of a positively charged spin probe and ESR spectroscopy and a fluorescent pH indicator and fluorescence spectroscopy show that actually the surface potential is not changed. A theory of the electrophoretic behaviour of vesicles in the presence of PEG is given which explains the contradiction between the two methods. It is assumed that the polymer is excluded from the vesicle surface (depletion layer) and that the viscosity near the surface is lower than the viscosity in the bulk phase. The thickness of the depletion layer is calculated from the experiments. The decrease of the zeta potential in the presence of poly(oxyethylene) chains linked to the vesicle surface results from the friction increase.
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The influence of the capacitation on the electric charge of the spermatozoal surface and the unspecific spermatozoon-oocyte-binding are not fully understood up to now. Therefore, human semen samples were divided into two subgroups of spermatozoa by the "swim up" method. Both of the subgroups were examined by means of the micro-electrophoresis and the immunofluorescence technique using antihuman fibronectin antibodies. Cellular electrophoresis: The 2 subgroups of spermatozoa prepared of one semen sample showed a significantly different electrophoretic mobility (EPM) after washing and resuspension in an isotonic glycin-HCl-buffer (pH 2.0). In contrast, after resuspension in Baker's-buffer (pH 7.4) no difference between the 2 subgroups of one semen sample was detectable. The incubation in a medium with Ca++ caused secondly alterations of the EPM with the result of a smaller difference between the two subgroups of spermatozoa. Albumin also modified the EPM of spermatozoa. Immunofluorescence technique: 69 per cent of spermatozoa with a normal shape and only 17 per cent of them exhibiting a pathological shape showed a positive fibronectin-fluorescent-band on the equatorial segment called equatorial fibronectin band (EFB). Spermatozoa separated by "swim up" from semen samples with various semen parameters showed different percentages of spermatozoa with EFB. There was a significant difference between the spermatozoa of the two subgroups after "swim up" concerning EFB.
Evaporation of tears occurs by diffusion, free (thermal), and forced convection. Under resting conditions only diffusion and free convection play a role. Therefore, a device should be applied with only these two parameters working. Creating a stationary known pressure gradient of water vapor over the eye, the evaporation rate was found to be 24.8 +/- 6.8 mg cm-2 h-1 in 21 test persons (no spectacle or contact lens wearers, no known general or eye disease, average age 25.6 years). The same test arrangement over a water surface of 1.7 cm2 gave a value of 43 mg cm-2 h-1 and simplified calculation, applying Fick's law of diffusion, 54 mg cm-2 h-1. These results suggest that there is a water vapor pressure of less than half the saturation water vapor pressure of less than half the saturation water vapor pressure corresponding to 32 degree C over the surface of the eye. Calculation yields a value of 230 mg per eye per 16 hours, corresponding to 32 degrees C (50% air humidity) over the surface of the eye and 22 degrees C (50% air humidity) room temperature. Assuming a tear secretion of 0.6 g per eye per 16 hours (Schirmer), about 40% of this amount evaporates under normal conditions.
In 82 experiments on 10 goats body core temperature (Tcore) was altered between 35 degrees and 42 degrees C by external heat exchangers acting on blood temperature while skin temperature (Tskin) was maintained constant, by a circulating shower bath, at different levels between 32 degrees and 44 degrees C. At all skin temperatures at least fourfold increases of heat production (M) and respiratory evaporative heat loss (REHL) occurred when Tcore was lowered or raised, respectively. The lower Tskin was, the higher were the thresholds of Tcore, at which M or REHL exceeded resting levels. The lower Tskin was, the higher were the slopes, at which M or REHL changed per unit of Tcore. At a given Tskin, the slopes decreased with increasing M or REHL, and were dependent on the range of Tcore. The higher the range of Tcore, the steeper changed M and REHL with changing Tcore, if all other variables were held constant. The results support the concept that an exponential relationship between Tcore and the rate of core temperature signals is the primary cause of the effects exerted by Tskin on the slopes, at which M or REHL change per unit of Tcore.
Cholesteric liquid crystals show different colors dependent on their temperature. The "thermography with liquid crystals" makes use of this property for the determination of temperature distributions of human skin. The correct photographic documentation of the color patterns is difficult, because the colors depend on the angle of incidence of light and the direction of observation. Further, the quality of the photos is reduced by the direct reflection of light at the surface. Possible geometrical conditions of taking photos are discussed. An optimum arrangement for producing photos without reflections and color changes is proposed.
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Explore the source record for details and available documents.